Ground contact time (GCT) is a very common measure in sports science, but it’s also an increasingly popular measurement with coaches who manage jump and sprint training. It is simply a measure of how long a foot is on the ground from the first point of contact on the Stomp-IT to the last point of contact just before takeoff and is a very practical way to see changes in training and improved performance in explosive tests such as the drop jump drop hop, 10/5 repeat jump, and 10/5 repeat hop but also to measure to ground contact time whilst running and walking over the Stomp-IT force plates.
GCT can also be considered as an input for how the jump is performed and is often very reliant on technique and the depth of the jump phase of the movement. Therefore when assessing for GCT practitioners should be aware of their instructions for the test. Eg: Are you asking the athlete to jump as high as possible (maybe a longer GCT) or asking the athlete to achieve as low a Ground Contact Time as possible (maybe a lower jump height).
In the case of Drop Jump testing the height of the drop should also be carefully standardised as the higher the drop height often the longer the GCT as it takes longer to control the eccentric overload from the landing.
Typically the lower the ground contact time, the more efficient the athlete is in suddenly transferring force from a landing to then take off, resulting in greater speed and power.
Research has suggested that results of <0.2 sec on a drop jump and <0.25 sec on a drop hop for power athletes should be aimed for, while results of <0.25 sec for a drop jump and <0.3 sec for a drop hop are appropriate for endurance athletes.